Once downloaded, its recommended to download it from your computer and place it on your phone, put it on the root of your internal or external sd card. Root meaning not in a folder.

Reboot into recovery using Quick Reboot.

Then scroll down to “Install Zip From Sd”, if you put the kernel on your external SD card select “choose zip from SD”. If you put it on your internal scroll down and select ‘choose zip from internal”. Then after you selected one of those depended on where you put the kernel, scroll down and select the kernel and then Select “Yes”.

Let it run and do its thing and once it says its done, select “reboot system now” and enjoy